Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Saturated core fault current limiters are known. For example, U.S. Pat. Nos. 7,193,825 and 4,045,823 disclose fault current limiters where a core is magnetically saturated during normal operation by a DC current and taken out of magnetic saturation during a fault condition. The saturated core fault current limiter relies upon the non-linear properties of high permeability saturation/de-saturation so as to suppress faults.
Unfortunately, a number of unwanted operational characteristics of such a fault current limiters are usually present during a fault condition. These can include excessive electromagnetic forces and/or fluxes which can occur during faults which provide excessive mechanical and electromagnetic stresses on the fault current limiter. Additionally, the magnetic fluxes generated can be coupled to any DC coil which is designed to normally saturate the core. The coupling can affect the ongoing saturation and limit the effectiveness of the fault current limiter.
These and other unwanted effects can occur with prior art fault current limiter devices.